This invention relates to an apparatus for regulating the supply of fiber quantities to a textile machine, particularly the quantities of fiber in a fiber lap fed to a card or a roller card unit (hereafter collectively referred to as a carding machine). The apparatus includes a measuring device extending over the width of a fiber layer surface for mechanically sensing the thickness deviations at several locations along the width. The sensed signals are, prior to comparing them with a predetermined desired value, combined by a mean value forming arrangement and, as a function of the deviation of the measured actual (mean) value from the desired value, the fiber quantity to be supplied to the textile machine is altered.
In a known apparatus of the above-outlined type excursions of levers connected with side-by-side arranged lap supporting trays represent thickness variations at several locations across the width of the fiber lap. The deflections of the individual levers are combined by means of a lever system and processed mechanically. Such a system, however, is structurally complex and its accuracy is inherently limited.